24 
ture seemed to have rather a beneficial effect on the caterpillars, 
which grew rapidly. When full-grown the larvse measure from 
eighty to ninety millimetres in length, or even more; they then 
select two or three leaflets which they fasten to the main stalk of 
the Ailanthus-leaf, and within the case thus formed spin their 
cocoons. The first of the specimens at Sheriff Hutton spun up on 
the 29th July; another began on the 31st, and by the afternoon of 
the 3rd August twelve had affeady spun their cocoons. Of the 
twenty specimens one died soon after they were put into the garden; 
three others died after the 14th August, apparently in consequence 
of a violent hailstorm ; and another, after feeding voraciously until 
the 22nd August, was found next morning in a dying state at the 
foot of the tree, probably killed by the great cold of the night. 
The whole of the cocoons (fifteen) were gathered on the 24th August, 
divested of their leafy covering, and suspended in a temperature 
rarely under 60° F. On the 23rd September the first moth 
emerged; it was mistaken for a Bat, and was captured with the 
tongs. This specimen (a male) lived for ten or twelve days; it 
was tranquil during the day, but in a state of excitement at night. 
On the 19th October another (male) Bombyx escaped from its cocoon. 
It is remarkable that although the silkworms when received were 
apparently of the same age, there was an interval of more than 
three weeks between the spinning of the first on the 29th July and 
. the death of the last, without spinning, on the 22nd August. In 
conclusion Lady Mary Thompson remarks :—“ The Ailanthus has 
been long known in England as an ornamental tree, bearing aU the 
changes of our variable climate; the silkworm, to judge by the 
limited experiment at Sheriff Hutton Park, can be raised in the 
open air, even in Yorkshire. It is scarcely, therefore, being too 
sanguine to hope, that at no distant time a new cultivation will be 
practised, which may contribute somewhat to the prosperity of the 
country.” 
Dec. 6. —In consequence of the death of the Earl of Carlisle, 
President of the Society, which occurred on the preceding day, the 
Monthly Meeting was adjourned to the 3rd of January. 
